First of all, the exhaust volume is not directly related to the engine displacement. What is most related to the exhaust volume is the geometry and volume of the exhaust system. For example, a pedal motorcycle with a displacement of 125cc (0.125l) can also make a loud noise after it is refitted to exhaust directly (common on the street), and the sound after removing the exhaust pipe is even louder.
The exhaust volume of sports cars is higher, which usually has the following two considerations:
Reduce exhaust resistance (i.e. exhaust back pressure)
Sports cars are often equipped with engines that pay more attention to power output at high speed, that is, engines with greater maximum power and maximum torque at the same displacement, so as to improve their power performance.
At high speed, low exhaust resistance can improve the inflation efficiency of the engine and enhance the power output. In order to improve the fuel economy of general household vehicle engines, more consideration is given to the torque output of the engine at low speed, because daily driving rarely has the opportunity to drive the speed above 3000rpm (too fuel consuming). This requires a higher exhaust back pressure to ensure the inflation efficiency of the engine at low speed.
The silencing effect of the exhaust system is contradictory to its exhaust resistance. The exhaust system with better silencing effect has larger volume, more complex internal cavity structure and greater exhaust resistance. Therefore, sports car engine equipped with exhaust system with poor silencing effect can be considered as a compromise to its power performance.
It should be noted that this difference in external characteristics is not only caused by the difference of exhaust system. But when designing the exhaust system, we should consider the characteristics of the engine itself for matching.
market factors
Simply put, people who buy sports cars just want to hear the "loud" exhaust sound.
1. People usually associate higher exhaust volume with stronger power performance (this is the motivation of many owners who buy household cars but refit straight exhaust people, even if they clearly know that such refitting is not necessarily conducive to power performance);
2. On the other hand, the loud exhaust sound is more noticeable, which meets the needs of owners who need luxury cars to show their identity. Therefore, the manufacturer will consider the preferences of most car owners and give their best, and specially adjust the exhaust system with high volume.
Of course, some people just buy sports cars for better handling and power. They don't want to make too much publicity. For these relatively few consumers, there are some relatively low-key sports cars on the market, such as Bentley, Jaguar and other brands. The exhaust volume is far less loud than that of Lamborghini, and the appearance is also dignified and stable.
The adjustment of the exhaust system is not the only goal of high volume. Its function is still the primary goal, just for sports cars, that is, to ensure that the engine outputs as much power as possible. In addition, the timbre and frequency distribution of sound need to be considered, which is a very complex work.
Appreciation of world sports cars:
renault
Porsche
bmw
Benz
Bentley
Ferrari
Lamborghini